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What to Expect When Starting Mestinon for Myasthenia Gravis

Last updated: August 2022

Medical Disclaimer: This content was created for generalized informational purposes only. This is not intended to be a substitute for professional medical advice, diagnosis, or treatment.

Pyridostigmine (Mestinon) is a drug used to treat muscle weakness in myasthenia gravis (MG). Though Mestinon is commonly prescribed for MG, patients still might have questions about what to expect when starting this treatment.

When will Mestinon start working?

When taken orally, pyridostigmine starts working within 15-30 minutes and its effects last for 3-4 hours. The greatest effect is usually seen 2 hours after administration.

How do doctors determine the dose?

The dosing schedule of pyridostigmine is individualized for every patient and can be adjusted over time as symptoms of myasthenia gravis change. For example, a patient with difficulty chewing or swallowing may only need to take pyridostigmine before meals, while a patient with severe generalized weakness may need higher doses throughout the day.

A typical starting dose is 30 MG 3 times per day. After several days of starting pyridostigmine, patients should note whether they are experiencing side effects - commonly diarrhea, stomach cramps, nausea, slowed heart rate, excessive salivation or sweating.

These are not all the possible side effects a patient may experience. If a patient is experiencing bothersome side effects, they should talk to their doctor as the dose or frequency can be reduced.

Additionally, ensuring the medication is taken with food can help reduce stomach upset and additional medications that combat side effects can be introduced. If a patient is tolerating pyridostigmine but still experiences myasthenia symptoms, the dose or frequency can be increased with guidance from their doctor.

If a patient reaches the maximum daily dose of pyridostigmine without improvement in symptoms, or they find side effects too bothersome, their doctor will likely recommended discontinuing pyridostigmine and starting immunomodulating therapy.

Coping with side effects

Every patient has a different threshold for what side effects they can tolerate. In general, life-threatening side effects warrant discontinuation. If non-life-threatening side effects are causing significant distress, discomfort, or are hindering daily functioning, then discontinuation or dose modification is advised.

If side effects are mild, not too bothersome, and coupled with good symptom control, then continuation is reasonable.

Keeping track of symptoms

Patients should report any new symptom to their doctor, even if they are unsure if it is related to their medication. Be vigilant reporting common side effects of pyridostigmine which can include stomach upset, diarrhea, excessive salivation/sweating, slowed heart rate, and muscle cramping.

Between appointments, it is important to keep track of what time of day your myasthenia symptoms flare and how well pyridostigmine is alleviating your symptoms. This information will help your doctor craft the best dosing schedule for you.

For example, you may notice that your symptoms are severe in the afternoon but well controlled in the morning - this can prompt your doctor to increase your afternoon dose.

Talking to your doctor

As doctors, our role is to present medication options to our patients, explain their risks and benefits, and provide an objective opinion. If a patient is unsure if a medication is right for them, I encourage them to voice their questions and concerns to their doctor and start a dialogue.

Be honest and do not worry about asking silly questions. Ultimately, the decision to start a medication is a personal choice, but exchanging information with their doctor doctor will help patients make the most informed decision possible.

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This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The Myasthenia-Gravis.com team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

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